Leonardo da Vinci sketched a helicopter-like flying machine with rotating spiral blades.
His design, usually called the aerial screw, appears in a manuscript from about 1489. It featured a large helical rotor made from reeds, linen, and wire. Leonardo theorized that turning the screw rapidly would make it rise by pushing against the air, much as a screw advances through a solid material.
The machine was not a helicopter in the modern engineering sense. It had no engine capable of supplying the necessary power, and the proposed rotor would not have lifted the full structure with its occupants. The sketch is nevertheless an important early example of the idea of vertical flight.
Leonardo’s aerial screw is sometimes incorrectly described as the first helicopter. Modern helicopters depend on powered rotors, aerodynamic control, and lightweight materials developed much later. Leonardo supplied a striking conceptual precedent, not a working aircraft.